Small mammal exploitation of upper vegetation strata in non-forest, mixed farmland habitats

In September 1998, activity of small mammals in upper herbal and shrub vege tation strata was examined and quantified in a standardized field experimen t using a paired upper stratum (height = 0.5 m) vs. ground stratum trapping design. Trapping took place across a range of different biotope types in a typical Danish mixed farmland within the Kolindsund area, Djursland, Denma rk. Seven small mammal species were encountered among the 409 catches during 77 6 trapnights. Upper vegetation stratum activity was considerable in Micromy s minutus and Apodemus flavicollis. Clethrionomys glareolus, Sorex minutus and Sorex araneus also exploited upper vegetation strata but only to a Less er extent. Microtus agrestis and Apodemus sylvaticus were only caught in gr ound stratum traps. Our results show that, at Low to moderate densities, some small mammal spec ies, such as M. minutus, may be greatly underestimated or entirely missed b y a traditional ground trapping grid. Therefore, the potential upper vegeta tion stratum activity in some small mammal species should generally be cons idered in studies performed in areas or seasons with vigorous herbal or shr ub vegetation suitable for climbing.